Track the path taken by tokens in combat and display it when reactivating DragRuler in the same turn

src/movement_tracking.js

@@ -0,0 +1,62 @@
+function initTrackingFlag(combatant) {
+	const initialFlag = {passedWaypoints: [], trackedRound: 0};
+	let dragRulerFlag = combatant.flags?.dragRuler;
+	if (dragRulerFlag) {
+		if (isNaN(dragRulerFlag.trackedRound)) {
+			mergeObject(dragRulerFlag, initialFlag);
+		}
+	}
+	else {
+		combatant.flags.dragRuler = initialFlag;
+	}
+}
+
+function getInitializedCombatant(token, combat) {
+	const combatant = combat.getCombatantByToken(token.data._id);
+	if (!combatant)
+		return undefined;
+	initTrackingFlag(combatant);
+	return combatant;
+}
+
+export async function trackRays(token, rays) {
+	// Only track movement if the current token is participating in the active combat
+	const combat = game.combat;
+	if (!combat)
+		return;
+	if (!combat.started)
+		return;
+	const combatant = getInitializedCombatant(token, combat);
+	if (!combatant)
+		return;
+
+	// Check if we have entered a new round. If so, remove the currently stored path
+	if (combat.data.round > combatant.flags.dragRuler.trackedRound) {
+		combatant.flags.dragRuler.passedWaypoints = [];
+		combatant.flags.dragRuler.trackedRound = combat.data.round;
+	}
+
+	// Add the passed waypoints to the combatant
+	const waypoints = combatant.flags.dragRuler.passedWaypoints;
+	for (const ray of rays) {
+		// Ignore rays that have the same start and end coordinates
+		if (ray.A.x !== ray.B.x || ray.A.y !== ray.B.y)
+			waypoints.push(ray.A);
+	}
+	await combat.updateEmbeddedEntity("Combatant", {_id: combatant._id, flags: combatant.flags}, {diff: false});
+}
+
+export function getMovementHistory(token) {
+	const combat = game.combat;
+	if (!combat)
+		return [];
+	const combatant = combat.getCombatantByToken(token.data._id);
+	if (!combatant)
+		return [];
+	const dragRulerFlags = combatant.flags.dragRuler;
+	if (!dragRulerFlags)
+		return [];
+	if (combat.data.round > dragRulerFlags.trackedRound)
+		return [];
+	return dragRulerFlags.passedWaypoints ?? [];
+}